The invention relates to the use of alkyl polyglycosides in printing ink cleaners. The invention further relates to a method of removing printing inks and/or oil residues which form on the surface of printing machines, printing plates and the like and also the associated equipment, in which the surface is treated with a cleaning composition comprising at least one alkyl polyglycoside.
EP 498 545 B1 describes a method of removing oil residues which form on the surface of printing machines, printing plates and the associated equipment, said method comprising the following step: treating the surface with a cleaning composition which comprises at least one C6 or higher alkyl ester of a fatty acid. In addition to these fatty acid esters, which function as the main constituent of the cleaning composition, other, complementary constituents may be present in the cleaning composition, examples being surfactants, emulsifiers, vegetable oils, fatty acid C1-5 alkyl esters, water, organic solvents, acids, bases, alkalis, buffer systems, sequesterants, and corrosion inhibitors.
WO 94/17143 describes cleaning compositions for removing unwanted paint and similar xe2x80x9ccoatingsxe2x80x9d from a substrate, said compositions comprising 5-membered ring lactams and also triglycerides of monocarboxylic acids having 1 to 4 carbon atoms.
WO 90/03419 describes the use of C1-5 alkyl esters of aliphatic C8-22 monocarboxylic acids for removing fat, ink and the like from printing machines, specially offset printing machines. Said esters are used preferably in a blend with vegetable oils and a surfactant. Said surfactant is preferably selected from the class of the polyglycol ethers of aliphatic C8-22 alcohols, very particular preference being given to adducts of from 7 to 14 mol of ethylene oxide per mole of a C12-22 fatty alcohol.
It was an object of the present invention to provide new, effective printing ink cleaners. In particular, the intention was to provide a method of removing printing inks and/or oil residues which form on the surface of printing machines, printing plates and the like and also the associated equipment.
It has surprisingly been found that alkyl polyglycosides, which belong to the class of nonionic surfactants are suitable, alone or in combination with other substances, for sustained removal of printing inks from solid surfaces. In particular, said alkyl polyglycosides are suitable for removing printing inks and/or oil residues which form on the surface of printing machines, printing plates and the like and also the associated equipment.
In the context of the present invention the term xe2x80x9csolid surfacexe2x80x9d is used in the sense that it embraces exclusively those applications where the surface to be cleaned is merely freed from unwanted deposits thereon, such as printing inks, printing ink residues, oil residues and the like but the surface per se is not destroyed in the course of this operation. Not part of the present invention, accordingly, are those applications where the removal of printing inks and the like is accompanied by substantial destruction or degradation of the surface, as is the case, for example, in the removal of printing inks from printed waste paper. In the case of this latter process, the paper used is not retained as such but instead, following the process, is in the form of fragments (paper fiber pulp).
The present invention provides for the use of alkyl polyglycosides (I)
R(G)xxe2x80x83xe2x80x83(I)
where R is a linear saturated alkyl radical having 8 to 22 carbon atoms and (G)x is a glycoside or oligoglycoside radical having a degree of oligomerization, x, of from 1 to 10 in printing ink cleaners.
The alkyl glycosides (I) are established surface-active substances which can be prepared from sugars and from aliphatic primary alcohols having 8 to 22 carbon atoms with acetalization. Suitable sugar components (glycoses) are preferably glucose, but also fructose, mannose, galactose, telose, gulose, allose, altrose, idose, arabinose, xylose, lyxose, libose, and mixtures thereof.
On account of their ease of availability and good performance properties, preference is given to the acetalization products of glucose with fatty alcohols obtainable, for example, from natural fats and oils by known processes, especially with linear primary saturated and unsaturated fatty alcohols having 8 to 22 carbon atoms.
As far as the glycoside radical (G)x is concerned, both monoglycosides (x=1), where one sugar radical is linked glycosidically to the fatty alcohol, and oligomeric glycosides, having a degree of oligomerization x=2 to 10, are suitable. In general, mixtures of monoglycosides and oligoglycosides are present.
Preferred and suitable alkyl glycosides (I) are those in which R is an alkyl group having 8 to 22 carbon atoms and (G)x is a glycoside or oligoglycoside radical having a degree of oligomerization x=1 to 10. With very particular preference, R is an alkyl group having 8 to 14 carbon atoms. The average degree of oligomerization is preferably within the range from 1 to 1.5.
In many cases, the extent of removal of printing inks from solid surfaces can be increased by using the alkyl polyglycosides of the invention in combination with fatty acid esters and/or with one or more surfactants. Said surfactants can be chosen from the classes of the anionic surfactants (except for alkyl polyglycosides (I), which of course are anyway a mandatory constituent of the compounds to be used in accordance with the invention). There are no restrictions whatsoever on the selection of the surfactant; in other words, all relevant anionic, cationic and nonionic surfactants known to the skilled worker can per se be used. The weight ratio of the compounds (I) to the optional constituents mentioned is in the range from 1:20 to 20:1.
In the presence of the alkyl polyglycosides (I) to be used in accordance with the invention it is possible to remove printing inks and/or oil residues, examples being rotary inks for newspapers, letterpress inks, offset inks, publication gravure inks, flexographic inks, laser printing inks and/or packaging gravure inks, from solid surfaces of printing machines, printing plates and the like.
The invention further provides a method of removing printing inks and/or oil residues which form on the surface of printing machines, printing plates and the like and also the associated equipment, which comprises treating said surface with a cleaning composition comprising at least one alkyl polyglycoside (I)
R(G)xxe2x80x83xe2x80x83(I)
where R is a linear saturated alkyl radical having 8 to 22 carbon atoms and (G)x is a glycoside or oligoglycoside radical having a degree of oligomerization, x, of from 1 to 10.
In one embodiment of this method, the alkyl polyglycosides (I) are used in combination with fatty acid esters (II) of the structure
R1xe2x80x94CO2xe2x80x94R2xe2x80x83xe2x80x83(II)
where R1 is a saturated or unsaturated straight-chain 10 or branched alkyl radical having 6 to 23 carbon atoms and the radical R2 is a saturated or unsaturated alkyl radical having 1 to 24 carbon atoms and/or with one or more surfactants.